Surface effects on the Formation of Hydrogen Peroxide from dissociated water vapour

The formation of hydrogen peroxide at 77°K from water vapour dissociated in a low-pressure electrodeless discharge was investigated as function of the surface-to-volume ratio. S/V, of both coated and uncoated tubular reactors interposed between the discharge exit and the coolant level. As S/V was increased, the peroxide yield increased to a maximum value and then decreased; this maximum shifted to much lower values of S/V for KCl-coated and H₃PO₄-coated surfaces. Compared with uncoated Pyrex surfaces, H₃PO₄-coatings gave higher H₂0₂ yields whereas KCl-coatings gave lower yields. Surfaces coated well with ice did not show much effect, but condensed water films decreased the H₂O₂ yield. Similar results were obtained when the surface area and the volume traversed by the dissociated vapour were varied at constant S/V. These surface effects are discussed to show that the formation of H₂O₂ occurs via the cold surface reactions H + O₂ → O_aH and H + 0₂H → H₂O₂ and not by the dimerization of OH radicals.     

Some asymptotic results in hydrodynamic lubrication theory

Exact and asymptotic solutions to Reynolds equation for one-dimensional hydrodynamic lubrication are obtained for the case of rigid bearing surfaces and pressure-dependent viscosity.     

A note on general core-valence orthogonality

A method of generating a set of basis functions, which satisfy the condition of strong orthogonality, is developed.     

Diophantine inequalities with mixed powers

It is shown that λ₁, λ₂,…, λ₆, μ are not all of the same sign and at least one ratio $\text{λ}{}_{\mathrm{i}}\text{λ}{}_{\mathrm{j}}$ is irrational then the values taken by $\text{λ}{}_1\text{x}{}_1{}^3\text{+ ? + λ}{}_6\text{x}{}_6{}^3\text{+ μy}{}^3$ for integer values of x₁ ,…, x₆, y are everywhere dense on the real line. A similar result holds for expressions of the form $\text{λ}{}_1\text{x}{}_1{}^3\text{+ ? + λ}{}_4\text{x}{}_4{}^3\text{+ μ}{}_1\text{y}{}_1{}^2\text{+ μ}{}_2\text{y}{}_2{}^3$.     

An evaluation of a sales training programme in a retailing environment

The effectiveness of a proposed sales training programme by a major High Street retailer is assessed using an experimental design which matches test and control stores and measures performance before and after training. The paper also discusses the significance of such programmes in today's shopping environment and the potential of experimentation in retailing.     

Impulse duration: A new instrument for its measurement

An instrument is described which, when used with a ‘peak hold’ reading sound level meter, will measure the durations of acoustic impulses in accordance with the Atherley and Martin and CHABA criteria for hearing damage risk to impulsive noise. The instrument is small, lightweight, can be battery powered and is designed for field use.Comparison tests show that the impulse duration meter gives more accurate and repeatable results than the oscilloscope trace photograph method or the digital waveform recorder method of impulse duration assessment.By using the instrument with a suitable impulse source reverberation time, measurements may be conducted.     

A unified constitutive model for superalloys

A physically based unified constitutive model is presented for an aircraft engine nickelbase superalloy. The model accounts for deformation modes that can be activated under different stress, time, and temperature combinations. Two internal state variables and a flow function have been utilized to prdict strain rate sensitivity, stress hold creep, strain hold relaxation, monotonic loading, cyclic loading, and thermal mechanical cycling. In the model flow function, creep deformation and plasticity deformation modes have been incorporated over a wide range of temperatures (0.4 < T/T_melt < 0.75). The model is checked with independent isothermal and thermal mechanical experiments. Different temperature ranges are explored to assess model capabilities.     

Spectral beam combining of a broad-stripe diode laser array in an external cavity

The outputs from an 11-element, linear diode laser array with broad stripes have been beam combined into a single beam with a beam quality of ~20x diffraction limited in the plane of the junction. This beam combining was achieved by use of a common external cavity containing a grating, which simultaneously forces each array element to operate at a different, but controlled, wavelength and forces the beams from all the elements to overlap and propagate in the same direction. The power in the combined beam was 50% of the output from the bare laser array.